Process of shrinking solid polymethylene terephthalate with halogenated methanes



PROCESS OF SHRINKING SOLID POLYMETHYL- ENE TEREPHTHALATE WITH HALOGENATED METHANES This invention relates to a process for shrinking oriented crystalline polymeric structures such a fibers, filaments, films, fabrics, feltsand the like comprising a polyester of the type disclosed in U.S. Patent No. 2,465,319.

The polyesters of the aforementioned patent have been utilized for the production of many commercial products. In their production several serious problems have arisen. One such is the difficulty in controlling the shrinkage of the structures. This problem is particularly acute in the manufacture of polyester felts and fabrics, since proper shrinkage of the felts and fabrics is necessary to impart satisfactory handle to the materials.

Numerous treatments have been used to overcome these various problems. However, most of these treatments have not been completely acceptable for one or more reasons, such as excessive cost of either the reactants or the equipment required for the treatments.

We have discovered an improved process for shrinking solid oriented crystalline polyester structures. This process comprises shrinking the structure by treating it with a normally liquid partially halogenated methane. The partially halogenated methane employed can be methylene chloride, chloroform, monochloromethane, chlorobromomethane, chloroiodomethane, tribromomethane, dibromomethane and the like. Because of their extremely fast action, ease of handling, and quick drying, the preferred agents are methylene chloride and chloroform.

This shrinking treatment is ordinarily carried on by submerging the oriented crystalline polyester structure in a liquid bath containing the partially halogenated methane in a liquid phase. Thus the treating bath can consist solely of one or more of the above described partially halogenated methanes. Alternatively, the bath can be an emulsion containing a partially halogenated methane liquid phase.

The minimum amount of partially halogenated methane present in the emulsion treatment bath is not critical so long as there is a distinct liquid phase of partially halogenated "methane. By way of example, an emulsion of methylene chloride in water can be used. Since methylene chloride is soluble in water in an amount equal to about 2% by weight at room temperature, a methylene chloride-water emulsion containing any amount in excess of about 2% by weight is satisfactory for practicing this invention at room temperature.

The particular temperature employed in practicing the method of this invention is not critical. It can be carried out at all temperatures ordinarily used for synthetic textile treatment.

While this shrinking process is adapted to the treatment of the polyester materials of the above mentioned patent, namely the various polymeric polymethylene terephthalate materials, it is particularly efiective when applied to polyethylene terephthalate structures. Consequently, the following examples are given showing the practice of this invention in connection with polyethylene terephthalate. It is to be understood, however, that this method is un tfld vStates 2,981,978 Patented May 2, 1961 m equally applicable to the treating of the various other polyesters set forth in the patent.

In order that the invention can be better understood, the following examples in addition to those given above are set forth:

Example 1 type batt is ideally suited for various air filtration uses.

A second batt sample prepared as above was immersed in a bath of methylene chloride at room temperature. This second batt also shrunk gradually and evenly 44% areawise to yield a uniform felted product substantially free from wrinkles.

A third sample was immersed in boiling water. This sample shrank immediately 44% in area, yielding a dense highly wrinkled product much inferior to the unwrinkled products treated with the partially halogenated alkanes.

Example 11 Fabric samples made from- 2 /2 inch staple 3-denier per filament oriented crystalline polyethylene terephthalate fibers were treated for 5 minutes at C. in an emulsion of 10% by weight methylene chloride in water. This treatment was carried on under pressure to avoid excessive volatilization of the methylene chloride. After dyeing in accordance with conventional procedure, it was found that the thusly treated fabric samples exhibited a much improved handle, as compared to untreated dyed control samples. Furthermore, the treated samples had shrunk considerably.

Example Ill Fabric samples were treated in accordance with the procedure of Example II, but using methylene bromide as the shrinking agent at atmospheric pressure. The same type of shrinkage and improved handle resulted.

Example IV A series of tests similar to those set forth in Example I were performed but with the methylene chloride treatment being carried on at temperatures ranging from 25 C. to 80 C. All the treated samples shrunk substantially and exhibited greatly improved handle.

Example V Another series of tests in accordance with the procedure of Example I was carried on but using a methylene chloride treating bath in place of the methylene chloride-water emulsion bath of Example I. The treated samples exhibited the same shrinkage and improved handle as the samples of Example I.

Results similar to those of Examples I thru V are obtained by substituting for the shrinking agents of these examples various other partially halogenated methanes, such as those set forth above. Likewise, in place of the polyester fabrics and batts of these examples, fabrics of blends of polyester fibers with other fibers, such as wool, cotton or a synthetic fiber, can be used with similar results. Thus it is apparent that this process for shrinking oriented crystalline polyester structures is subject to numerous modifications all of which are within the scope of the invention.

wherein X is halogen and each Y is selected from the group consisting of hydrogen and halogen, until the said structure shrinks.

2. The method in accordance with claim 1 wherein said structure is a fabric.

g Theterm oriented crystalline polyester structures refers to structures comprising poly- 3. The method in accordance with claim 1 wherein X 0 is chlorine.

4. The method in accordance with claim 1 wherein said structure is a film.

5. The method in accordance with claim 1 wherein which comprises subjecting said formed article to stretching, and thereafter subjecting the stretched article to treatment for 15 seconds to 5 minutes with methylene chloride.

7. A process of improving a formed article formed from a high polymeric polyethylene terephthalate, which comprises subjecting said formed article to stretching, and

thereafter subjecting the stretched article to treatment for 15 seconds to 5 minutes with methylene chloride. References Cited inthefile of this patent UNITED STATES PATENTS 2,730,478 Morgan Jan. 10, 1956 2,734,001- Mecklenburgh Feb. 7,. 1956 2,856,638 Schulken Oct. 21, 1958 FOREIGN PATENTS 553,442 Great Britain May 21, 1943 555,490 Great Britain Aug. 25, 1943 578,079 Great Britain June 14, 1946 

1. THE METHOD OF SHRINKING A SOLID CRYSTALLINE ORIENTED HIGH POLYMERIC POLYMETHYLENE TEREPHTHALATE STRUCTURE COMPRISING CONTACTING IT WITH A NORMALLY LIQUID PARTIALLY HALOGENATED METHANE OF THE FORMULA 